Preliminary findings from a clinical trial of heavy drinkers suggest that the drug can weaken certain memories tied to the reward of imbibing, although the mechanisms aren’t fully clear.

Nov 27, 2019

The anesthetic drug ketamine could be used to rewire heavy drinkers’ memories and help them cut down on alcohol consumption, according to a study published yesterday (November 26) in Nature Communications. In a clinical trial of people who reported consuming around 590 grams of alcohol—equivalent to nearly two cases of beer—per week on average, researchers found that a procedure that involved administering the drug while people were thinking about drinking durably reduced consumption.

While it’s not clear how the method works at a neurological level, the study represents “a really exciting development,” Amy Milton, a behavioral neuroscientist at the University of Cambridge who was not involved in the work, tells STAT. She adds that the findings mark “the first time it’s been shown in a clinical population that this can be effective.”

The study was designed to manipulate the brain’s retrieval and stabilization of memories—in this case, those linking the sight and thoughts of alcohol to the reward of drinking it, study coauthor Ravi Das, a psychopharmacologist at University College London, tells Science News. “We’re trying to break down those memories to stop that process from happening.”

To do that, the team asked 30 of the participants to look at a glass of beer, followed by a sequence of images of alcoholic and non-alcoholic drinks. On the first day of tests, the session ended with participants being invited to drink the beer. On the second day, after viewing the beer and images, the screen cut off, and instead of drinking the beer, participants were given a shot of ketamine.

Among various functions, ketamine blocks NMDA receptors—key proteins in the brain’s reward pathways—so the researchers hypothesized that administering the drug during memory retrieval would help weaken participants’ associations between the sight or contemplation of alcohol and the reward of drinking it. Their results somewhat support that hypothesis. Nine months following the several-day trial, the volunteers reported cutting their drinking back by half.

“To actually get changes in [participants’] behavior when they go home and they’re not in the lab is a big deal,” Mary Torregrossa, a neuroscientist at the University of Pittsburgh who was not involved in the work, tells Science. But she notes that it’s not clear whether it was the ketamine or some other part of the procedure that led to the effect.

Another 60 participants, split into two control groups, received slightly different procedures that involved either beer or ketamine and still showed, on average, a 35 percent decrease in alcohol consumption after nine months. The participants themselves were recruited to the study through online ads—meaning that the researchers may have selected for people already interested in reducing consumption.

Whatever the mechanisms behind the effect, the results so far suggest the method is worth investigating, David Epstein, an addiction researcher at the National Institute on Drug Abuse, tells Science News. “If a seemingly small one-time experience in a lab produces any effects that are detectable later in real life, the data are probably pointing toward something important.”